Radiation generation system for electronic radiation valves with ionic trap



Nov. 20, 1956 B. HENSEL 2,771,564

RADIATION GENERATION SYSIVIEM FOR ELECTRONIC RADIATION VALVES WLTH IONIC TRAP Filed Feb. 15. 1954 Fig.7

F792 Q W United States Patent RADIATION GENERATION SYSTEM FOR ELEC- TRONIC RADIATION VALVES WITH IONIC TRAP Bernhard Hansel, Berlin-Friedman, Germany, assignor to Loewe Opta Aktiengesellschaft, Berlin-Steglitz, Germany, a company of Germany Application February 15, 1954, Serial No. 410,103 Claims priority, application Germany February 16, 1953 1 Claim. (Cl. 31382) In nearly all modern electron beam tubes, particularly those functioning as television receiving tubes, the practice has been adopted of having the electronic beam run at first oblique to the actual axis of the valve and of then guiding it back into the direction of the axis by magnetic means, so that in this way the ionic portion of the electronic beam, which is not included by the return guidance is kept away from the screen surface of the valve. The oblique position, at the beginning, of the electronic beam can be achieved by placing the preliminary system, which usually consists of cathode, Wehnelt cylinder and first anode, obliquely, or else by having a preliminary system which runs along the axis of the valve, and which contains at least one electrode which is cylindrical or diaphragmatic, of which the marginal surface or the entire surface is inclined to the plumb level of the axis of the tube.

In the drawing:

Fig. 1 shows in sectional form a part of an electrode system according to the known art,

Fig. 2 in sectional form a part of an electrode system according to the present invention.

In Fig. 1 the cathode 1 which lies in the axis of the valve or parallel to it is surrounded by a Wehnelt-cylinder 2 for the purpose of electronic control, the face of said cylinder has a beam exit opening 3. A short distance behind this Wehnelt-cylinder 2 the first anode 4 is arranged, which most suitably has the form of a perforated disc with a central aperture 5. The ionic trap effect in these well-known electrode systems is achieved by providing the diaphragmatic part 4 of the first anode with a cylindrical fitting 6, of which the side away from the cathode is bevelled and also equipped with a perforated disc 7. This perforated disc 7, which if necessary can reach to the inner neck wall of the electron beam tube, results in the deflection of the electronic beam generated by the cathode, which remains deflected until deflected back with the aid of a magnetic field (not shown).

Now a first anode of the form shown in Fig. 1 is technically diflicnlt to manufacture. It is particularly diflicult to place the cylindrical portion 6 with bevelled outer edge against the first perforated disc 4, and then to attach the plate 7 to this.

The difficulties mentioned are avoided in the present invention by the fact that the first anode no longer consists of one piece which is formed by the two perforated discs and the cylindrical portion which connects them, but that rather the first and the second perforated discs are manufactured as separate elements, and are attached separately in the tube system. According to this invention, the electrical connection between these two perforated discs is not achieved by the cylindrical electrode part shown in Fig. 1, but through a simple wire connection which brings both perforated discs to the same potential.

The drawing shows in Fig. 2 a sample construction of the invention applied to an electronic beam valve for television purposes. This drawing shows only the parts necessary for understanding the invention, in a schematic manner: A cathode 1, in or parallel to the axis of the valve, is provided, behind which, looking in the direction of the beam, is the Wehnelt-cylinder 2 with its central opening 3. According to the invention, the first anode consists of a perforated disc 4 which first runs parallel to the plumb level of the radiation axis, and a second perforated disc 8 which is at a distance of a few millimeters, in the direction of the beam, behind this disc. Preferably, this perforated disc 8 should be able to extend sidewise to the inner wall of the valve. There is a short electrical connection 9 provided between both perforated discs, for example in the shape of a simple wire welded to the electrode plates.

The two anodes, together with cathode and Wehneltcylinder, are most suitably located on a common ceramic carrier 11, which has, for example, the form of a cylinder, in the inner wall of which the disc 4 is set, and the outer edge of which is bevelled in such a way that the second plate of the first anode can be placed on this bevelled edge, for example so that it borders the face edge of the cylindrical carrier.

What I claim is:

An electrode system for electron beam tubes with ionic trap in which the first anode is shaped as a perforated diaphragm and is inclined against the plumb level of the beam axis, said first anode consisting of a perforated plate arranged vertical to the radiation axis and a second perforated plate inclined to said axis and connected with the first plate by an electrical conductor, said first perforated plate being arranged inside a cylindrical ceramic carrier, the face of which pointing in the direction of radiation is bevelled and carries said second perforated plate.

References Cited in the file of this patent UNITED STATES PATENTS 

